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Câu a bạn haphuong01 làm sai kìa
2xy(x-3y) mới đúng
Hoc24h vẫn cho đúng là sao
Hy vọng GV hoc24h chấm cẩn thận hơn nha
minh cung lop 8
x^3-xy^2-6xy^2+6y^3
=x(x^2-y^2)-6y^2(x-y)
=x(x-y)(x+y)-6y^2(x-y)
=(x-y)(x(x+y)-6y^2)
ban cu hoc thuoc HẰNG ĐẲNG THỨC LÀ RA NGAY CO J CỨ HỎI MINH MINH CHUYEN TOAN , ANH , HOA
1) 2x2 - 4x = 2x( x - 2 )
2) 3x - 6y = 3( x - 2y )
3) x2 - 3x = x( x - 3 )
4) 4x2 - 6x = 2x( x - 3 )
5) x3 - 4x = x( x2 - 4 ) = x( x - 2 )( x + 2 )
1) \(2x^2-4x=2x\left(x-2\right)\)
2) \(3x-6y=3\left(x-2y\right)\)
3) \(x^2-3x=x\left(x-3\right)\)
4) \(4x^2-6x=2x\left(2x-3\right)\)
5) \(x^3-4x=x\left(x-2\right)\left(x+2\right)\)
a)\(=3x\left(x+2y\right)\)
c)\(=\left(x-7\right)\left(x-1\right)\)
b)\(=x\left(x-2y\right)+3\left(x-2y\right)=\left(x+3\right)\left(x-2y\right)\)
d)\(=\left(2x\right)^2-y^2=\left(2x-y\right)\left(2x+y\right)\)
\(a,3x^2+6xy=3x\left(x+2y\right)\\ c,x^2-8x+7=\left(x^2-x\right)-\left(7x-7\right)=x\left(x-1\right)-7\left(x-1\right)=\left(x-1\right)\left(x-7\right)\\ b,x^2-2xy+3x-6y=\left(x^2+3x\right)-\left(2xy+6y\right)=x\left(x+3\right)-2y\left(x+3\right)=\left(x+3\right)\left(x-2y\right)\\ d,4x^2-y^2=\left(2x-y\right)\left(2x+y\right)\)
a) Ta có: \(x^2-2xy+y^2-2x+2y\)
\(=\left(x-y\right)^2-2\left(x-y\right)\)
\(=\left(x-y\right)\left(x-y-2\right)\)
b) Ta có: \(x^2-4x+4-x^2y+2xy\)
\(=\left(x-2\right)^2-xy\left(x-2\right)\)
\(=\left(x-2\right)\left(x-2-xy\right)\)
x2 - x - y2 - y
= (x - y)(x + y) - (x + y)
= (x + y)(x - y - 1)
***
9x2 + y2 - 16z2 + 6xy
= (3x + y)2 - (4z)2
= (3x + y - 4z)(3x + y + 4z)
***
a3 - a2x - ay + xy
= a2(a - x) - y(a - x)
= (a - x)(a2 - y)
***
2x2 - 8y2 + 3x + 6y
= 2(x2 - 4y2) + 3(x + 2y)
= 2(x - 2y)(x + 2y) + 3(x + 2y)
= (x + 2y)(2x - 4y + 3)
***
xy(x + y) + yz(y + z) + xz(x + z) + 2xyz
= xy(x + y + z) + yz(x + y + z) + xz(x + z)
= y(x + y + z)(x + z) + xz(x + z)
= (x + z)(xy + y2 + yz + xz)
= (x + z)[y(x + y) + z(x + y)]
= (x + z)(x + y)(y + z)
\(1,\\ 1,=15\left(x+y\right)\\ 2,=4\left(2x-3y\right)\\ 3,=x\left(y-1\right)\\ 4,=2x\left(2x-3\right)\\ 2,\\ 1,=\left(x+y\right)\left(2-5a\right)\\ 2,=\left(x-5\right)\left(a^2-3\right)\\ 3,=\left(a-b\right)\left(4x+6xy\right)=2x\left(2+3y\right)\left(a-b\right)\\ 4,=\left(x-1\right)\left(3x+5\right)\\ 3,\\ A=13\left(87+12+1\right)=13\cdot100=1300\\ B=\left(x-3\right)\left(2x+y\right)=\left(13-3\right)\left(26+4\right)=10\cdot30=300\\ 4,\\ 1,\Rightarrow\left(x-5\right)\left(x-2\right)=0\Rightarrow\left[{}\begin{matrix}x=2\\x=5\end{matrix}\right.\\ 2,\Rightarrow\left(x-7\right)\left(x+2\right)=0\Rightarrow\left[{}\begin{matrix}x=7\\x=-2\end{matrix}\right.\\ 3,\Rightarrow\left(3x-1\right)\left(x-4\right)=0\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=4\end{matrix}\right.\\ 4,\Rightarrow\left(2x+3\right)\left(2x-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{3}{2}\\x=\dfrac{1}{2}\end{matrix}\right.\)
\(x^2+4x-9y^2+4\)
\(=\left(x^2+2.2x+2^2\right)-\left(3y\right)^2\)
\(=\left(x+2\right)^2-\left(3y\right)^2\)
\(=\left(x+2-3y\right)\left(x+2+3y\right)\)
\(x^2-9y^2-6y-1\)
\(=x^2-\left[\left(3y\right)^2+2.3y+1^2\right]\)
\(=x^2-\left(3y+1\right)^2\)
\(=\left(x-3y-1\right)\left(x+3y+1\right)\)
Tham khảo nhé~
a/Ta có:x2+4x-9y2+4
=x2+4x+4-(3y)2
=(x+2)2-(3y)2
=(x+2-3y)(x+2+3y)
b/Ta có:x2-9y2-6xy-1
=x2-6xy-(3y)2-1
=(x-3y-1)(x-3y+1)
x^2 - 2x - 15
= x^2 - 5x + 3x - 15
= ( x^2 + 3x ) - (5x +15 )
= x ( x +3 ) - 5 ( x + 3 )
(x + 3 ) ( x - 5 )
a) 2x - 6y = 2(x - y)
b) 4x2 + 6xy2 = 2x (2x + 3y2)
c) 5a (x+1) - 10b (x +1)
= (x + 1) (5a - 10b)
=5 (x +1) (a -2b)